1. Field of the Invention
The present invention relates to a fluid agitation apparatus for reducing temperature fluctuation, and a thermostatic apparatus using the fluid agitation apparatus.
2. Description of the Related Art
In recent years, there has been required nanometer-order positioning and processing accuracy for semiconductor exposure apparatuses and ultra-precision machining apparatuses, and along with this, there has been required temperature stability of the apparatus at a tolerance of ±0.001° C.
In order to stabilize the temperature of the apparatus at a constant temperature, a thermostatic chamber is generally prepared to circulate air controlled at a constant temperature. However, even when the temperature of the gas (for example, air) introduced into the thermostatic chamber fluctuates, the temperature of the thermostatic chamber fluctuates, which may reduce the temperature stability of the apparatus.
In order to reduce such temperature fluctuation, there has been proposed a fluid agitation apparatus capable of reducing temperature fluctuation of a fluid in a cross section on a downstream side of a fluid passage. Examples of the conventional fluid agitation apparatus include a fluid agitation apparatus for agitating a fluid through use of a movable member such as a propeller, and as exemplified in FIG. 3, a fluid agitation apparatus for agitating a fluid by generating a circumvolving flow in the fluid through use of a fluid passage which is processed into a spiral shape (see, for example, Japanese Patent Application Laid-Open No. 58-177126).
In the conventional fluid agitation apparatus using the movable member as described above, there has been a problem that the temperature may still fluctuate due to heat generated in a sliding portion of the movable member. Further, in the conventional fluid agitation apparatus using the fluid passage processed into a spiral shape as exemplified in FIG. 3, there have been problems that the shaping process and the like become complicated, and a given length is required in the fluid passage direction so as to obtain a sufficient effect of reducing temperature fluctuation.